Paperboard container for liquids



March 3, 1970 H. B. MOORS mL 3,498,527

PAPERBOARD coNTAiNER FOR LIQUIDs F IGLI,

2 Sheets-Sheetl 1- Filed sept. 28. 1967 March 3, 1970 H. B. Moons ETALPAPERBOARD CONTAINER FOR LIQUIDS 2 Sheets-Shaml 2 Filed Sept. 28, 1967FIGB.

FIGA.

N D T CG xA IN AN Tl G ST WM A 2 Lm D. 5 PC IMl PLASTIC COATINGPAPERBOARD HEAT souRcE CoA-ren IIIIIIIIIlIl-Pll United States Patent O3,498,527 PAPERBOARD CONTAINER FOR LIQUIDS Harold B. Moors, Richboro,William E. Schwenk, Norristown, William J. Crothers, Jr., Exton, andJames N. Ademino, Ambler, Pa., assignors to International Papergonllpany, New York, N.Y., a corporation of New or Continuation-in-partof application Ser. No. 454,935,

May 11, 1965. This application Sept. 28, 1967, Ser.

Int. Cl. B65d 5/72, 5/40 U.S. Cl. 229-48 8 Claims ABSTRACT OF THEDISCLOSURE Paperboard containers, and blanks for assembling suchcontainers, in which the paperboard surface is coated and the portion ofthe uncoated edge, in a substantially continuous line at the bottom ofthe Iside seam and bottom seam, is impregnated with a thermoplasticmaterial, such as wax, so that such impregnated edge is liquid repellentwhen exposed to the liquid contents of the assembled container and themethod for making such containers by heating the edge of the containerand contacting such heated edge with the impregnating material.

This application is a continuation-impart of U.S. application Ser. No.454,935, filed May 11, 1965, now abandoned and relates to paperboardcontainers and methods for making such containers.

Paperboard containers are widely used for packaging a variety of liquidproducts, such as, milk, juices, Syrups, and the like, and are erected,or assembled, from banks cut from paperboard stock coated on one or bothsurfaces with a protective coating of thermoplastic material, `such as,wax, or polyethylene. Such blanks are embossed so that, when foldedalong the embossed lines in erecting or assembling the container, topand bottom closures and side walls are formed. Ordinarily, suchcontainers are folded and side seamed, by machine, and the folded andseamed blank is shipped flat to the iiilling point. The at, 'seamedblank is opened up, the bottom of the blank is folded and sealed, thecontainer is filled with the desired liquid, and the top of thecontainer is then folded and sealed. All of this is usually done wherethe container is iilled and by machine.

There are many geometrical configurations in which the blank may be cutand embossed to form such a container and the instant invention is notconcerned with any particular configuration. In all such configurations,however, the blank is cut from precoated paperboard `stock and, whencut, raw, or uncoated paperboard edges are left around the blank. Whenfolded into the container, certain of these raw, uncoated, paperboardedges are exposed to, and in cnotact with, the liquid contents of thecontainer.

The paperboard stock is relatively thin and the raw, or uncoatedpaperboard edge exposed to the liquid contents in the container isrelatively narrow. It has been discovered, however, that during shipmentof such paperboard containers with some liquids, for example, orangejuice, vibration of the container and its liquid contents causes aslight, but substantially continuous, liexure in the side wall at thebottom of the container to seep or and that this vibration causes theliquid in the container wick into the raw, uncoated and exposed edge ofthe paperboard, weaken the structure of the container and cause leakageof the liquid.

One of the objects of this invention is to provide an improvedpaperboard container for liquids.

Patented Mar. 3, 1970 Another object is to provide a method for makingsuch container.

A further object is to provide such a container, and method, in whichthe paperboard edge at the side and bottom of the seam is sealed againstleakage.

Still a further object is to provide a blank from which such containercan be erected, or fabricated, on machines presently in use.

These and other objects will be more apparent from the followingdescription and the appended drawings in which:

FIGURE 1 is a plan view of a container blank in accordance with theinstant invention;

FIGURE 2 is a perspective view Iof the bottom of a container assembledfrom the blank of FIGURE l showing the bottom closure, as the containeris being assembled;

FIGURE 3 is an enlarged plan view, partly in section, of a fragment ofthe container of FIGURE l showing in enlarged detail the impregnation ofthe paperboard blank;

FIGURE 4 is an enlarged cross sectional view taken along lines 4-4 ofFIGURE 3;

FIGURE 5 is a view, in side elevation, of a schematic illustration ofthe method of the instant invention, and

FIGURE 6 is a top plan view of the schematic illustration of FIGURE 5.

There are many geometrical shapes and sizes of coated paperboardcontainer blanks of which the container blank illustrated, andhereinafter described, is but one. Irrespeetive of the igeometricalshape of the blank, and as will be better understood from the followingdescription, containers assembled from such blanks have, exposed to theliquid in the container, a paperboard edge. The instant invention isconcerne-d with such exposed edge and not with the particular shape ofthe blank.

Referring now to FIGURE 1, ilat blank 2, cut from a larger sheet ofcoated paperboard, is embossed at vertical lines 4, 6, 8, 10 into bodypanels 12, 14, 16 and 18 and side seam panel 20. Each panel, 12 through20, is divided by embossed horizontal lines 22, 24, approximatelyperpendicular to embossed lines 4, 6, 8, 10, into top sections 12a, 14a,16a, 18a, 20a, side sections 12b, 14b, 16b, 18b, 20b, and bottomsections 12e, 14e, 16C, 18C, 20c. Each of the top sections is embossedalong fold lines to form, when folded, a top closure. Furtherdescription of the top sections is not necessary for an understanding ofthe instant invention.

Side sections 12b, 14b, 16b, 18b,f20b and bottom sections 12c, 14C, 16e,18C, 20c form the vertical sides and bottom of the assembled container.Bottom sections 14o, 18e are each divided into triangular shapedsections, by embossed diagonal lines 30, 32 and 34, 36. Thus, bottomSection 14c is divided into three triangular portions 38, 40, 42 andbottom section 18e into three triangular portions 44, 46, 48.

Conventionally, the paperboard container blank is assembled, or erected,by machine, part of the assembly occurring after the blanks are cut andembossed and the balance occurring where the containers are filled. Forease and convenience in shipping and storage, it is customary practicefor the manufacturer of the blanks to fold the blank, seal the side seamand ship the folded blank liat. The folded and side seamed blank isopened into the rectangular container, the bottom closure is folded andsealed, the container is filled and the top closure is folded and sealedwhere the containers are filled. All of these folding and sealingoperations are performed by conventional machines, not described here.

In the initial assembly of the blank, the surfaces of side panel 12 andseam panel 20 which, when brought into contact with each other, adhereand form a liquid tight seam, are heated to soften the thermoplastic, orpolyethylene, coating and side panel 18 is folded onto side panel 16along embossed line 8. Seam panel 20 projects beyond embossed line 6onto side .panel 14. Side panel 12 is then folded along embossed line 4onto side panel 14 and the heated surface at the end of side panel 12 isbrought into contact with the heated surface of seam panel 20. Pressureis then applied to seam panel 20 and the thermoplastic coating is cooledto form a liquid tight seam between the mating surface of panels 12 and20. The folded and seamed blanks are then packaged and shipped.

As the containers are to be filled, the balance of the assembly, orerection, of the containers is completed. The seamed blanks are openedout into a rectangular container, end panels 14, 18 are folded alongembossed lines 30, 32 and 34, 36, respectively, and inwardly alongembossed lines 24 toward the center of the container, end panels 12, 16are folded inwardly and the end of the container is sealed. Thecontainer is then filled and the top sections are folded inwardly andsealed. The `filled containers can then be shipped.

As shown in FIGURE 4, the container blank is made up of a paperboardcenter coated on its opposite faces with a thermoplastic coating, suchas polyethylene. When the blank is cut from the paperboard sheet andembossed, the thermoplastic coating on the opposite faces of the sheetremain intact and form a liquid proof barrier, or coating, on the facesof the blank. However, the cut edges of the paperboard center of theblank are uncoated and exposed. Thus, the edge of seam panel 20 which,when the container is assembled, is in the inside of the container, willbe exposed to the liquid contents of the container.

In the instant invention, the paperboard between the thermoplastic, orpolyethylene, coatings is impregnated with a thermoplastic material,such as wax, after the container blank is cut from the coated sheet andembossed and before the initial assembly or erection of the container.As best shown in FIGURES 1 to 4, the paperboard core 50 is impregnatedat 52 with wax in a continuous area extending above and below embossedline 24 and into the paperboard core. As will be described, thisimpregnation is accomplished after the paperboard core is coated and theblank is cut from the coated sheet. The impregnation does not interferewith the coating, nor with conventional erection and sealing, butprevents wicking or wetting of the paperboard core by the liquidcontainer contents and weakening of the seam and leakage resultingtherefrom.

Referring now to FIGURES and 6, container blanks 2 are stacked, one onthe other, and the edges of the container blanks to be impregnated areadvanced past the front of heat source 60. The edge portion to beimpregnated is heated to a temperature receptive to the impregnate, butnot high enough to soften and cause sticking of the thermoplasticcoating on the surfaces of the blanks. With the edge portion thusheated, the thermoplastic material, such as Wax, is brought into contactwith the heated edge and the wax is taken up, absorbed or adsorbed bythe paperboard core. Preferably, the wax is heated and brought intocontact with the paperboard edge by an application, such as coaterroller 62 rotated, in the direction of the arrow in FIGURE 5, throughheated wax supply reservoir 64. Treated cartons are removed from thebottom of the stack by conveyer 6-6.

The thermoplastic material, or wax, in the treatment of the paperboardedge at the bottom area of the side seam and at the bottom seam of theinstant invention, is taken up and flows into the paperboard between thethermoplastic coated surfaces and migrates through the edge into thepaperboard. The depth of migration into the paperboard and length of theedge treated can, of course, be varied so long as the line ofimpregnation is continuous and extends through the fold between the sideand bottom.

Migration of the thermoplastic material to a depth not less thanone-sixteenth of an inch and not greater than four-sixteenths of aninch, in a continuous path along the side and bottom seals of notsubstantially less than one and eleven-sixteenths of an inch and notsubstantially more than two and ten-sixteenths of an inch, with the pathcontinuous and divided substantially equally between the side and bottomseams, has been found satisfactory. A depth of migration of one-eighthof an inch and a continuous path of two inches, divided substantiallyequally in the side and bottom seams, is preferred.

The thermoplastic material taken up by the paperboard core in the areatreated makes the edge of the board liquid repellent or hydrophobic inthe treated area but does not interfere with the assembly, or erection,and sealing of the container in the conventional manner. Furthermore,when the bottom panel is folded to form the bottom closure, the treatededge retains its liquid repellency. The container, when filled, may beshipped over extended distances and stored for prolonged periods evenwhen filled with liquids, such as orange juice, that have, in the past,been found to be most prone to leakage from coated paperboardcontainers.

202,000 one quart paperboard container blanks, cut from paperboard stockcoated on its opposite surfaces with polyethylene were treated inaccordance with the instant invention. The container blanks werestacked, one or the other, and advanced in a continuous stream so thatthe edge of the blanks to be impregnated advanced past a heater andheated to a temperature not substantially less than F. and notsubstantially more than 130 F. The area of the edge to be impregnatedwas thus heated and parain wax, maintained at a temperature of plus orminus 2 F., was brought into contact with the heated edge of thecontainer blank as the blanks advanced past the applicator. The treatedblanks were then removed.

Approximately 58,000 container blanks were treated for each pound of waxconsumed. The average depth of wax penetration into the edge of thetreated blanks was 3/16 of an inch and the average length along the edgeof the blank was 2% inches. The containers were assembled by machine inthe conventional manner, tested for side seam bonding and bottomsealing. The seams were found well bonded and the bottoms properlysealed. The containers did not leak.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible.

What is claimed is:

1. A coated paperboard container blank intended to be erected into acontainer for liquid and having portions to be included in side walls,bottom walls, and a side and bottom wall sealing seam of an erectedcontainer, said blank having a paperboard edge which, when the containeris erected, will be in said side and bottom sealing seam and exposed tothe liquid contents of the erected container, and a thermoplasticimpregnate material in said paperboard edge extending inwardly into thepaperboard in said sealing seam portion behind the coating on saidpaperboard and extending axially in a continuous path in said paperboardedge behind said coating from a point in the side wall portion of saidsealing seam to a point in the bottom wall portion of said sealing seam.

2. A coated paperboard container blank as recited in claim 1, in whichsaid thermoplastic material is wax.

3. A coated paperboard container blank as recited irl claim 2, in whichsaid thermoplastic material extends inwardly into the edge of saidpaperboard for not substa11-i tially less than one-sixteenth of an inchand not substantially more than four-sixteenths of an inch.

4. A coated paperboard container blank as recited in claim 3, in whichsaid thermoplastic material extends axially into said edge of saidpaperboard in a continuous path in said paperboard edge notsubstantially less than one and eleVen-sixteenths of an inch and notsubstantially more 4than two and ten-sixteenths of an inch dividedsubstantially equally between said side and bottom sealing seamportions.

5. A coated paperboard container for liquid having side walls, a bottomWall, a side sealing seam extending along one of said side walls intothe bottom wall, a paperboard edge exposed in said container to saidliquid contents extending along said sealing seam, and a thermoplasticimpregnate material in said paperboard edge extending inwardly into thepaperboard in said sealing seam portion behind the coating on saidpaperboard and extending axially in a continuous path in said paperboardedge behind said coating from a point in the side Wall portion of saidsealing seam to a point in the bottom wall portion of said sealing seam.

6. A coated paperboard container as recited in claim 5, in which saidthermoplastic material is wax.

7. A coated paperboard container as recited in claim 6, in which saidthermoplastic material extends inwardly into the edge of said paperboardfor not substantially less than one-sixteenth of an inch and notsubstantially more than four-sixteenths of an inch.

8. A coated paperboard container as recited in claim 7, in which saidthermoplastic material extends axially into said edge of said paperboardin a continuous path in said paperboard edge not substantially less thanone and eleven-sixteenths of an inch and not substantially more than twoand ten-sixteenths of an inch divided substantially equally between saidside and bottom sealing seam portions.

References Cited UNITED STATES PATENTS 2,290,741 7 1942 Eckert 117-37 XR2,279,382 4/ 1942 Swenson. 2,282,898 5/ 1942 Snader et al. 117-372,415,387 2/ 1947 Graebmer et al. `2,474,619 6/ 1949 Farrell et al.

3,081,213 3/1963 Chinn. 3,116,002 12/ 1963 Crawford et al 229-173,189,246 6/ 1965 Seline 229--17 DAVIS T. MOORHEAD, Primary ExaminerU.S. Cl. X.R. 229--3.1

P04050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,098,527 Dated March 3, 1970 Inventads) Moors et al.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Col. l, line 56, "cnotact" should read contact --5 lines 65-66, shouldread "the side wall at the bottom of the container and that thisvibration causes the liquid in the container to selnp or";

Col. Ll, line 29 "or" should read on SIGNED AND SEALED n JUL 2 81970(SEAL) Attest:

Edwrd M' dan WILLIAM E. somma, JR. Attestng Officer onmissioner of hunts

